The present invention generally relates to a method for manufacturing a semiconductor device, and more specifically, to a method for forming a capacitor of a semiconductor device.
Recently, a DRAM device of high capacity has been used as a semiconductor memory device. The DRAM device comprises a transistor and a capacitor. The DRAM device includes a memory cell region for storing data with charges and a peripheral circuit region for inputting and outputting data.
However, it is difficult to provide capacitance of the capacitor as the design rule is smaller due to high integration of the memory device.
As a result, a lower electrode of the capacitor is configured to have a three-dimensional structure such as a cylinder structure and a concave structure.
In the cylinder structure, a storage node region is formed, and a Titanium Nitride (TiN) film is deposited in the storage node region to form the lower electrode. A full dip-out process is performed to remove an oxide film. A dielectric film and an upper electrode are formed.
However, the integration of the memory device has been increased, so that a width of the electrode becomes smaller and a height of the electrode becomes higher.
When an etching process is performed to form a storage node region, a lateral etching process causes a bowing phenomenon where the middle of the storage node region becomes wider than the top of the storage node region.
A minimum bar critical dimension which is a distance between the neighboring storage nodes is smaller because of the bowing phenomenon, which results in bridges.
Although the minimum bar critical dimension is increased to prevent bridges, a margin lacks in the etching process for forming a storage node region to generate a not-open phenomenon.
Although an etching characteristic has been strengthened, the bowing phenomenon occurs so that the minimum bar critical dimension is decreased.